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Homes being swallowed up by sinkholes is something most people would expect to see in a horror film, yet similar stories are making the headlines with alarming regularity and the problem is only getting worse.

Sinkholes are opening up everywhere from Cheltenham to Liverpool and even London, bringing into question much of what conveyancers (and the general public) thought they knew about mining and the risks it poses to ground stability in the UK.

Are you making dangerous assumptions about local mining risks?

South Wales, Cornwall and the North East are well-known locations for historical mining activity, prompting local conveyancers to stay aware of the connected risks. Yet those working in central and eastern England and London are less concerned – and even assume there aren’t any risks that will affect their clients’ properties which couldn’t be further from the truth.

Mining activity has taken place across the UK for 100’s of years with the availability of minerals shaping the growth of towns and cities the length and breadth of the country, as well as shaping their unique character (which is why the likes of Bath and Worcester look so different). The reality is that historical mining could affect almost any location in the UK so professional due diligence is essential when purchasing a property.

Forgotten shafts

Unlike the high-profile strikes surrounding the closure of the coal mines in the 1980’s, many other local mines across the country closed quietly during the turn of the 20th Century with the last large-scale mines closing in the 1960’s. With no legislation in existence or money to fill them in, 98% of these mines were abandoned and forgotten.

At the time, local communities remembered where the mineshafts had been located and therefore the land was used as open areas for parks rather than homes. As time has worn on much of this information has been lost and the open spaces unknowingly bought up and built upon by developers after which ground stability problems have emerged. Lack of data and expert professional interpretation, as well as NHBC regulations (which only require due diligence of the top 2m of the ground) have contributed to this risky oversight resulting in costly repair bills for developers and in extreme cases entire developments have been demolished such as the Bayfield, West Allotment Site in Tyneside.

Cases in point

Recent sinkholes in Reading, St. Albans and Kent serve as a stark reminder as to the risk historical mining activity can have on ground stability.

Houses, shops and schools that have, in most cases, unwittingly been built above these old mine shafts are suffering from a number of issues, such as subsidence and the appearance of collapses and mining sinkholes.

Here are just some of the examples that have made the headlines in recent years:

30 homes were evacuated in Reading when an old chalk mine collapsed

In January 2000, a 19th Century chalk mine collapsed causing major subsidence of the overlying ground around the Field Road and Coley Road area in Reading.

30 homes were evacuated for residents’ safety and a further 2 homes later collapsed. It took 12 years to fill the underground chalk mines with 1,742 tonnes of grouting, costing approximately £4.3 million.

Several shops were forced to close when a mining sinkhole appeared in Kent

In early 2015 at Lawrence Square, Northfleet, Gravesend, Kent, the appearance of a sinkhole forced several shops to close and 7 sets of council tenants to be evacuated for fears of more subsidence.

Continued subsidence forced the gas supply to be shut off and the area was declared unsuitable for permanent habitation. The area was heavily mined for chalk and clay during the 19th Century with many chalk mines and mining-related sinkholes already known in the immediate area around Lawrence Square.